Another glitch that happened to me recently (and spiked my weird-o-meter off the scale) was trying to MIG a couple of small parts that were held together by one of those large on/off fabrication magnets. Lessee now...gas on? Yup. Wire feed rate correct? Uh huh. Ground clamp secured to base workpiece? You betcha. Helmet on & activated? Absolutely!
Fire up old sparky, approach workpiece, press trigger, and...a spectacular light show, sparks & miniature lightning running up & down the magnet, across one workpiece and up the other, tiny little ball bearings of welding wire bouncing and rolling all over the place, all cycling over and over.
Look around shop, search for hidden practical joker/hidden camera. Nope, I'm all alone. Not even Rod Serling (cue "Twilight Zone" theme, for those old enough to remember the show).
Reset everything, try again. Same result. Hmmm. Head scratching time (take helmet off first).
Near as I can figure, the magnetic field was strong enough to draw off the molten beads of weld wire before they could fuse to the workpiece, effectively breaking the arc/melt/fuse cycle. Hence, no weld at all.
Anyone else had this happen???